Abstract: An exposure amount control device for controlling an integrated exposure amount of pulsed light to a photosensitive substrate within a predetermined range in which a pattern of a mask is successively exposed on the substrate by synchronously scanning the mask forming the pattern to be exposed and the photosensitive substrate relatively with respect to a predetermined illumination area illuminated with pulsed light from a pulsed light source, satisfies the following relationship:.DELTA.D.sub.12 .gtoreq.D/(2N.sub.min)wherein luminous intensity distribution of the predetermined illumination area in a scan direction is shaped to be a trapezoid, .DELTA.D.sub.12 is an average value of half of the widths of the slope portions on the lateral sides of the trapezoid-shaped luminous intensity distribution in the scan direction, D is the width, at half peak value points, of the luminous intensity distribution on the predetermined illumination area of the substrate in the scan direction and N.sub.